Staying loyal to Horizontally-Opposed Boxer engines, Subaru revealed their new generation of flat-four engines which will be available as 2.0 and 2.5 liter versions powering different models. The traditional features of boxer engines that are boosted in new edition include lightweight, compact, low center of gravity, and superior vibration balance. Subaru says the new engine offers 10% improvement in fuel efficiency, and driving performance.
The New-generation Subaru Boxer engine
- The bore and stroke, the basic structure of this engine, have been reviewed to achieve a compact combustion chamber as well as a long stroke, which was difficult previously due to chassis mounting conditions in boxer gasoline engines. This allows high combustion efficiency, and generates a sufficient mid-low speed torque with improved fuel efficiency and practicality.
- Improved fuel efficiency has been achieved through optimization of intake port configuration and the addition of partitions inside ports, the use of TGV (Tumble Generated Valve), and the use of an EGR (Exhaust Gas
- Recirculation) cooler.
- AVCS (Active Valve Control System) is used on both intake and exhaust valves. For the intake side in
- particular, an intermediate lock system allows valve timing to be advanced or delayed for precise control over intake and exhaust valve timing, allowing maximum engine performance in output, fuel efficiency, and exhaust emission.
- The use of lightweight primary moving parts, such as pistons and connecting rods, and a highly efficient and compact oil pump provides an approximately 30% reduction in friction loss and improves fuel efficiency and
- revolution response.
- Cooling has been optimized by using separate engine cooling circuitry for the block and the head, resulting in improvements in fuel efficiency and output characteristics.